64 GB Kingston Pen drive problem

Hello,
recently I purchased one kingston pendrive of 64GB from Nehru Place Delhi. I verified its capacity at the shop itself on computer. later when i copied some files on pendrive. it start showing the files on the pendrive. However if I remove the pendrive and again connect it with coputer, every thing simply disappears. The pendrive remains empty and showing full available capacity. I could not understand the reason.